Mirror twins?

Ah thanks nevermore I knew that the cat thing had to do with the nifty fur patterns but it was tossed out by the behavioral genetics prof to help illustrate the point before moving on.

Why are genetic mosaics only limited to females? I mean only one set of chromosomes in males are XY the rest as I understand it are XX? So these XX chromosomes should be able to switch between inactive and active genes as well? Right?

what book are you reading, Sua?